The UK says it will not oppose moves to upgrade the Palestinians to a non-member observer state, but foreign secretary William Hague says he wants a number of assurances first.

Mr Hague says the Palestinians must seek to negotiate with Israel without pre-conditions.

"In the absence of these assurances, the United Kingdom would abstain on the vote," he said.

"This would be consistent with our strong support for the principle of Palestinian statehood, but our concern that the resolution could set the peace process back."

Mr Hague says the Palestinians will also have to pledge not to sue Israel for war crimes through the International Criminal Court (ICC), and confirm the UN resolution will not apply retroactively.

"Up until the time of the vote itself, we will remain open to voting in favour of the resolution if we see public assurances by the Palestinians on these points," Mr Hague told parliament.

He said the guarantees sought by Britain would "not be difficult to make" and could be made either in the text of the Palestinian resolution, or in accompanying statements.

But it looks likely Britain will abstain after a Palestinian official said there would be no changes to the resolution before the vote.

"I can assure you that the text has been tabled, it will not be modified," Hanan Ashrawi, a senior member of the Palestine Liberation Organisation, said.

Mr Hague's comments highlight European divisions on the vote.

France has led several European countries in supporting the Palestinian bid for their UN status to be upgraded to that of a "non-member state", which would win them new global recognition.

Germany says it will not vote in favour of the bid.

Even without Britain's vote, the Palestinians are poised to win the backing of a majority of the General Assembly's 193 member states, although they face strong opposition from the United States and Israel.

Along with France, European supporters of the Palestinian upgrade include Spain, Norway, Denmark, Greece and Switzerland.

Lithuania has said it will abstain on the vote, which would give the Palestinians the same diplomatic status at the UN as the Vatican.